Bone involvement is a common, painful, and debilitating aspect of systemic masocytosis. It is not clear why systemic mastocytosis causes bone pain in the absence of fractures; however, long delays in making the diagnosis of systemic mastocytosis are not unusual and may allow progression of bone disease. Histopathologic patterns of bone marrow mast cell involvement have been identified as 1) focal mast cell aggregates in peritrabecular and perivascular areas often with increased numbers of eosinophils, and a dense network of reticulin fibers; 2) peritrabecular and perivascular sheets of mast cells accompanied by fibrosis and osteosclerosis; or 3) diffuse infiltration by atypical mast cells with marked hypoplasia of fat cells and blood precursors. This is a Phase I study to examine the effectiveness of low-dose mithramycin to relieve bone pain in patients with systemic mastocytosis. The clinical response to mithromycin will be evaluated by assessment of pain status and pain medication use prior to and following treatment. Functional status will be monitored with the Health Status Questionnaire (HSQ). Patient recruitment has been frustrating. The reason is not entirely clear, but I believe it is due to several factors: 1) patient resistance to pay expenses for travel to Rochester and preliminary costs for diagnosis of systemic mastocytosis; and 2) the normal ebb and flow of patients with rare disease who are seen at one institution. I have announced this protocol in the Mastocytosis Society Newsletter and have made announcements on the Mastocytosis Society's web page. I have been in touch with numerous physicians who refer patients with mastocytosis and have informed them of the study. I have also called patients directly to discuss the protocol.. I believe we will get the patient enrollment, but the time course of this enrollment is not clear.